Spanish prime minister Pedro Sánchez announced that he is willing to use his veto power to block Theresa May’s draft Brexit agreement with the EU if his concerns about the future status of Gibraltar are not addressed.

The Spanish premier stressed that he is willing to block the UK’s Brexit deal with the EU if Madrid is not given written assurances that it will have a say over any future trade agreements between the UK and the EU that will apply to Gibraltar.

‘My government will always defend the interests of Spain. If there are no changes we will veto Brexit,’ he added.

May’s uphill battle ahead of Sunday’s summit

The issue is yet another hurdle for May to clear ahead of a summit with EU leaders on Sunday, where she is hoping to finalise the exit agreement with Brussels.

EU Commission president Jean-Claude Juncker had reassuring words on Thursday saying that May was ‘working constructively’ with Spain on the issue and that she remains ‘confident that we’ll be able to agree a deal that delivers for the whole UK family, including Gibraltar’.

May faces a lot of hostility towards her draft Brexit agreement, with several senior ministers resigning in response to her plan, including Brexit secretary Dominic Raab and Work and Pensions secretary Esther McVey.

Can May make deal palatable to the people?

The prime minister is scheduled to appear on Radio 5 and BBC News at lunchtime on Friday with the intention to garner support from British voters for her Brexit deal.

If she can muster up support for her plan from the public then it will help her to get her deal through parliament, which is likely to heavily scrutinise her Brexit proposal.